Have only just joined and appreciate only just coming into this. For medical reasons I cannot ride a road bike. Again for medical reasons I have been advised that cycling would be the best form of exercise. I settled on a steel frame designed with 29 inch wheels in mind. I cannot afford two bikes and the road bike option was out. However I wanted/needed a bike to do both road and off. Initially the bike was fitted with suspension forks, however they developed a fault and had to go back to the supplier to be fixed. I was not prepared to wait so I fitted a solid pair of steel forks, I have not gone back to the sus forks. After a good deal of searching and a couple of poor buys I found tyres that were happy on both tarmac and off road, so long as its not too muddy! Maxxis Crossmarks. I feel I now have the perfect do anything bike. It will quite happily "take on" and stay with a road bike on tarmac when I am feeling energetic ! It will also turn quite happily off tarmac straight on to dirt track, forestry etc and belt along at a good speed or just trundle, again depends on how energetic I am. Yes, it cannot go down hill at great speed over rough ground but it is great fun nonetheless. I have found you soon learn to pick the best route. So to answer your question how limiting ? Get the right frame, 29 inch wheels and the bike will go anywhere there are no limits !

Had a Rockhopper for ever. When it came to replacing I opted for a CX bike. Shoved some Mavic wheels on along with Schwalbe Pro tyres. It really is fabulous offroad and I often use it to commute 15+ miles every other day. Love it. The bike's a steel Croix De Fer.

If you're clumsy enough to ride into a deep hollow with a lot of weight on the front, suspension can get you out the other side where a rigid would have you over the handlebars. Very rough descents can be taken a bit quicker too but that might not be a good thing!

james-o wrote:Not very, or not as much as some would suggest, unless you define mountain biking by the speed across technically demanding trails.

Most (almost all?) MTBs are designed to use a sus fork so they may feel more jarring at the front than they need to when a rigid for is fitted. http://www.jonesbikes.com/bike_design.html - An example of how to design a comfy rigid bike - these bikes may not be that readily available or a practical option for all, but from experience I'd say the ideas work and the design is sound. Better than sound really. Worth a read for perspective anyway. Basically, get your weight back and away from the front wheel, use bigger width and diameter tyres and consider adjusting your hand/wrist angle by using different bars to help adapt to the different demands. Suspension is great but it's not essential, I don't use it for most of my riding these days.

Seconded (if your pockets are deep enough)

I love mine with either it's skinny wheel on the front

Or it's fat wheel up front for more technical trails if speed isn't as important but fun is

I wouldn't do this on a full susser, but Jeff the builder doesn't seem to mind it being a rigid bike

Watch out for narrow frames as these only take a 1.9 tyre size. Look for a bike with wide rear forks, you want at least the thickness of your pinkie on each side of the tyre at the bottom and top of the rear frame. Minimum tyre size is 2.10 for off roading, cheap bikes do not always take this size. For a mountain bike secondhand buy two as you can use the forks with suspension and a disc brake on the best frame, [one a non suspension frame, the other a rigid frame, combining the two makes a good mountain bike], the frame has to be the same depth at the forks as it a straight swap. Combining the two should result in a mountain bike with a hardtail, no rear suspension with a decent v-brake, Shimano Acera are cheap and fit a decent cable brake such as the Tektro IO or similar to the front suspension forks plus replace the disk with an Aztec or any decent make. Wheels can be got from woollyhatshop.com Shimano Megarange gears from sjsjcycles.co.uk- derailleurs and freewheels. For a good all round tyre try the Schwalbe Marathon Plus MTB, perfect for older bikes. E-mail me at womblebikesscotland@outlook.com for more help.

As the OP, some of the early posters were correct in guessing that my interests laid more in pootling off road touring than full on MTBing. For the past year or so I have been enjoying riding an old rigid Rockhopper for this purpose which has been great fun.

I thank all the posters for their responses and I particularly like some of the more adventurous pictures